Technical Field
The present invention relates to a semiconductor device.
Background Art
The semiconductor device includes a plurality of power semiconductor elements and is used as a power converter or a switching device. The semiconductor device has semiconductor chips including IGBTs (insulated gate bipolar transistors), MOSFETs (metal oxide semiconductor field effect transistors), or the like connected together to be able to function as a switching device.
Silicon carbide (SiC) has seen particularly frequent usage recently as a constituting material for MOSEFETs. In a MOSFET made of silicon carbide, a parasitic diode is embedded in the top of the device structure. When this type of MOSFET is operated and current continually flows to the parasitic diode, stacking faults (SFs) grow from basal plane dislocations (BPDs) in the SiC wafer, the SiC epitaxial layer, or both. This is known to increase the ON resistance of the MOSFET and degrade reliability of the MOSFET (see Non-patent Document 1, for example).
As a countermeasure, ordinarily, a freewheeling diode such as a Schottky barrier diode (SBDs) made of silicon carbide can be connected in parallel to the silicon carbide MOSFET to reduce the flow of current to the parasitic diode of the MOSFET. This inhibits the growth of stacking faults in the MOSFET.
The growth of stacking faults also occurs in IGBT device structures.